Refrigerant Design Problem

Synopsis

The enumeration of large, combinatorial search spaces presents a central conceptual difficulty in molecular design. To address this difficulty, we develop an algorithm which guarantees globally optimal solutions to a mixed-integer nonlinear programming formulation for molecular design. The formulation includes novel structural feasibility constraints while the algorithm provides all feasible solutions to this formulation through the implicit enumeration of a single branch-and-reduce tree. We use this algorithm to provide the complete solution set to the refrigerant design problem posed by Joback & Stephanopoulos (1990) In addition to rediscovering CFCs, the proposed methodology identifies a number of novel potential replacements of Freon 12. All of the identified alternatives are predicted to possess thermodynamic properties that would result in a more efficient refrigeration cycle than obtained via the use of Freon 12.